SSL on Synology DSM 6.0...zeroSSL, other client?

I’m not wedded to zeroSSL. I just want this done lol. Is there a direction you can point me in for TLS? I don’t think port 443 is blocked. Just port 80 for me.

I don’t think I can do DNS verification since I’m using my ISP DNS. I don’t have access to the records.